Sanitary installation elements which are arranged in a water line are already known in an extremely wide variety of embodiments. For example, jet regulators have already been created which can be inserted into the water outlet of a sanitary outlet fitting. The previously known jet regulators, which are either fastened directly in the water outlet of a sanitary outlet fitting or can be inserted into an outlet mouthpiece which can be mounted on the water outlet, often have a jet splitter which divides the water flow flowing in through the pipe line and the fitting body into a multiplicity of individual jets. Said individual jets may, depending on the jet regulator design, be aerated if required before a homogeneous, soft and non-sputtering water jet is formed at the water outlet in a homogenization device which is situated downstream of the jet splitter and/or in an outflow-side flow straightener, which has a network-like, grate-like, sieve-like or honeycomb-like structure.
In order that the jet regulator can perform its function optimally and can form the water jet emerging from the water outlet, it is necessary for a certain quantity of water to flow through the jet regulator. Since the jet splitter and if appropriate also the downstream functional units of the jet regulator form a flow resistance, there is the risk at low pressures that a sufficient water quantity cannot flow through the jet regulator, and the jet regulator cannot perform its function, and that the water jet emerging from the jet regulator is perceived as being unpleasant.